Is Ubigi good for Japan?

Yes — Ubigi is one of the strongest eSIMs for Japan specifically because of its network. It's owned by NTT (Japan's largest telecom) through Transatel, and its Japan plans route through NTT Docomo, the country's most reliable mobile network. You get consistent signal in subways, rural areas, and mountains where eSIMs on secondary carriers can struggle. The trade-off is price: Ubigi costs more per GB than competitors like Saily that use the same Docomo network.

How much does a Ubigi eSIM for Japan cost?

Ubigi's Japan eSIM plans start at $6 for 1GB (30 days), $13 for 3GB (30 days), and $29 for 10GB (30 days). All plans run on NTT Docomo with hotspot support and a generous 30-day validity window. Frequent travelers can also use Ubigi's auto-renewing subscription plans, which lower the per-GB cost by roughly 15–20%.

Does Ubigi use NTT Docomo in Japan?

Yes. Ubigi's parent company NTT owns NTT Docomo, so Ubigi's Japan plans connect directly to Docomo's network — the largest and most reliable in Japan. Expect 40–80 Mbps on 4G/LTE in Tokyo and Osaka, with strong coverage in rural areas and underground stations.

Is Ubigi or Saily better for Japan?

Both run on NTT Docomo, so network quality is comparable. Saily is cheaper — its 10GB Japan plan is about $18 versus Ubigi's $29 — and has a more modern app. Ubigi's edge is its direct NTT ownership, longer-standing carrier relationships, and subscription plans for repeat travelers. For a one-off trip on a budget, Saily wins on price. If you specifically want NTT-backed infrastructure or travel to Japan regularly, Ubigi is worth the premium.

Does Ubigi offer unlimited data in Japan?

No. Ubigi sells capped data plans (1GB, 3GB, 10GB) with fixed allowances. If you want genuinely unlimited data in Japan, Holafly is the better fit — its unlimited Japan plans start at $19 for 5 days, though they run on SoftBank rather than Docomo and don't support hotspot.

Can I use Ubigi for hotspot/tethering in Japan?

Yes. Ubigi's Japan plans support hotspot and tethering, so you can share your connection with a laptop or a travel companion's phone. This is an advantage over some unlimited competitors that block tethering.

How do I activate a Ubigi eSIM for Japan?

Buy the plan on Ubigi's site or app before you travel, then install the eSIM by scanning the QR code (Settings → Cellular → Add eSIM on iPhone) or through the Ubigi app. Keep your home SIM as the active data line until you land in Japan, then switch your data line to Ubigi. The 30-day validity starts on first connection to the Docomo network.

Does Ubigi work in rural Japan and on the bullet train?

Generally yes. Because Ubigi runs on NTT Docomo — which has the broadest rural and tunnel coverage of any Japanese carrier — it holds signal better than eSIMs on secondary networks in places like the Japanese Alps, rural Hokkaido, and Shinkansen tunnels. No network is perfect in long mountain tunnels, but Docomo is the best bet.

Ubigi Japan eSIM Review: Coverage, Pricing & Setup (2026)

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The Short Answer

Ubigi is one of the best eSIMs for Japan— but for a specific reason. It's owned by NTT, the parent of NTT Docomo, so its Japan plans ride Japan's most reliable network directly. You get rock-solid signal in subways, rural areas, and mountains. The catch: Ubigi costs more per GB than Saily, which uses the same Docomo network for less. Buy Ubigi if you want guaranteed NTT-grade reliability or travel to Japan often; pick Saily if you just want the cheapest Docomo plan for one trip.

Check Ubigi Japan Plans→

What Is Ubigi?

Ubigi is a travel eSIM brand operated by Transatel, a Paris-based mobile connectivity company that became a subsidiary of NTT(Nippon Telegraph and Telephone) in 2019. NTT is Japan's largest telecom and one of the biggest in the world. That ownership is the whole story for Japan travel: Ubigi isn't reselling someone else's roaming agreement, it's plugged into the parent company of NTT Docomo.

Founded in 2013, Ubigi predates the current eSIM boom by several years — it started in connected-device and laptop data before pivoting to travelers. The upside is mature carrier relationships and genuinely good network quality. The downside, which we'll get to, is a buying experience that feels a generation behind Airalo and Saily.

Ubigi Japan Plans & Pricing

Ubigi keeps its Japan lineup simple — three capped data tiers, each with a generous 30-day validity window and hotspot support. Prices below are current as listed on AvailSim's Japan comparison.

Data	Validity	Price	Per GB
1 GB	30 days	$6.00	$6.00/GB
3 GB	30 days	$13.00	$4.33/GB
10 GB	30 days	$29.00	$2.90/GB

The 30-day validity on even the 1GB plan is unusually generous — most competitors cap their smallest plans at 7 days. For a short trip where you mostly use Wi-Fi and just need maps and messaging, the $6 / 1GB plan is genuinely useful. Frequent Japan travelers can also opt into Ubigi's auto-renewing subscription plans, which shave roughly 15–20% off the per-GB cost.

The NTT Docomo Advantage

This is the reason to consider Ubigi for Japan over anyone else. Japan has three major networks — NTT Docomo, SoftBank, and KDDI (au) — and Docomo has the broadest coverage, especially in rural areas, subway tunnels, and the mountainous interior. Ubigi routes its Japan plans through Docomo directly, courtesy of the NTT ownership.

In practice that means 40–80 Mbps on 4G/LTE in Tokyo and Osaka, strong signal on the subway, and far fewer dead zones if your itinerary heads into the Japanese Alps, rural Hokkaido, or along the Shinkansen. eSIMs that route through SoftBank or secondary carriers can drop signal in exactly those places.

The honest caveat: Saily also runs on NTT Docomo in Japan, for less money. So the network advantage isn't unique to Ubigi — what's unique is Ubigi's direct NTT relationship and its track record of Docomo routing over many years. If raw network is all you care about, Saily gets you onto the same towers cheaper.

How to Set Up Ubigi for Japan

Ubigi's setup is standard eSIM, with one quirk: the buying flow is web-first, so don't be surprised if the website is smoother than the app.

Buy before you fly

Purchase your Japan plan on Ubigi's website or app while you're still on home Wi-Fi, ideally 24–48 hours before departure. Ubigi's purchase flow is web-first — the site is often smoother than the app.

Install the eSIM profile

Scan the QR code Ubigi emails you, or install directly through the Ubigi app. On iPhone this lands under Settings → Cellular → Add eSIM; on Android under Settings → Network → SIMs.

Label it and leave data roaming on

Name the line something like "Ubigi Japan" so you can tell it apart from your home SIM. The Ubigi profile needs data roaming enabled to connect to NTT Docomo — that's expected and won't cost extra.

Activate when you land

Ubigi's Japan plans run on a fixed 30-day validity that starts on first connection. Keep your home SIM set as the data line until you arrive, then switch your data line to Ubigi after landing at Narita, Haneda, or Kansai.

New to eSIMs entirely? Our step-by-step eSIM setup guide walks through iPhone, Samsung, and Pixel in detail.

Ubigi vs Alternatives for Japan

Here's how Ubigi stacks up against the other top Japan eSIMs at the 10GB tier. The pattern is clear: Ubigi wins on network pedigree, Saily wins on price for the same network, Airalo wins on app polish and carrier flexibility, and Holafly is the pick only if you need unlimited data.

Provider	Network	10GB Price	Notes
Ubigi	NTT Docomo	$29.00	Direct NTT ownership; premium Docomo routing.
Saily	NTT Docomo	$17.99	Same Docomo network, noticeably cheaper.
Airalo	Docomo / SoftBank / KDDI	$21.00	Widest carrier mix; most polished app.
Holafly	SoftBank	—	Unlimited from $19 (5 days); no hotspot.

Want the full side-by-side with live prices across every tier? See the Japan eSIM comparison or the complete Ubigi provider review.

Pros & Cons for Japan

What we like

Routes through NTT Docomo — Japan's broadest, most reliable network (subways, rural areas, mountains)
Owned by NTT via Transatel — carrier-grade infrastructure, not a resold MVNO layer
Long 30-day validity on every Japan plan, including the 1GB tier
Hotspot/tethering supported and top-ups available mid-trip
Subscription plans for frequent Japan travelers (auto-renew, lower per-GB)

What to weigh

Pricier per GB than Saily, which rides the same NTT Docomo network for less
Web-first purchase flow and a dated app vs Airalo or Saily
Email/portal support only — no 24/7 live chat
Data-only (no calls/SMS) and no genuinely unlimited option

The Verdict

Ubigi is the eSIM I'd recommend to two kinds of Japan travelers: anyone heading off the beaten path — rural Hokkaido, the Alps, long Shinkansen legs — where Docomo's coverage edge genuinely matters, and frequent business travelers who'll use the subscription plans. Its NTT pedigree is real, not marketing.

For a first-time eSIM buyer on a single Tokyo-and-Kyoto trip, I'd be honest: Saily gets you onto the same NTT Docomo network for about $11 less at 10GB, with a friendlier app. The premium for Ubigi only pays off if you value the direct NTT relationship, the long 30-day validity, or you're a repeat visitor. There's no wrong answer here — both are genuinely good Japan eSIMs.

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Ubigi Japan eSIM Review